The company also rejected suggestions that a wi-fi network in a coffee shop below the ombudsman's offices was responsible for the first telecoms anomaly uncovered during the sweeps.

It said a wi-fi device on a secure internal wireless local area network and used to transmit audio, video or data - such as the one in the ombudsman's office - should not be attached to and communicate with any device outside its own secure network.

Verrimus said it could not comment on details of the work it carried out for Gsoc but wanted to correct technical inaccuracies.

Three security concerns were identified at the Gsoc's central Dublin offices last year but a subsequent investigation by its own officers could not find definitive proof.

A retired high court judge is expected to be named to lead the inquiry.

Mr Callinan clashed with the findings of a previous inquiry by a high court judge - the Smithwick tribunal - which found Garda collusion in the IRA double murder of RUC commanders Bob Buchanan and Harry Breen.

He said he will never accept judge Peter Smithwick's finding that some gardai valued loyalty to the force over the truth.

The Gsoc bugging scandal emerged after Verrimus carried out counter-surveillance sweeps on the watchdog's offices last September and then conducted a follow-up check.

It suspected government level surveillance technology was in use around the Gsoc offices.

Its experts found three security concerns - one was a wi-fi device - described as a media console - in the boardroom which was found to be connected to an external network.

Although it is not known how this happened, the device was not used by Gsoc and it could not connect to any of the watchdog's internal systems or databases.

Another was a suspected bug on the chairman Simon O'Brien's landline in his office which could not be traced.

The third was an ISMI catcher device which was imitating a UK 3G network around the Gsoc offices in central Dublin and could have been used to intercept calls and data on a mobile phone activated by the signal.

In response to reports that the analysts' own phones were the source of the unidentified 3G network and that the coffee shop below the ombudsman's offices was responsible for the wi-fi anomaly, Gsoc reiterated that none of the security concerns could be that easily explained.

The ombudsman repeated findings from its report on the controversy amid suggestions its telecoms were compromised through innocent interception of wi-fi at the coffee shop and the counter-surveillance teams' mobile signals.

Gsoc said that analysis of the threats was inconclusive.

"Gsoc did not rule out that there could be reasonable explanations for any or all of these issues," it said.

On the concerns about a wi-fi system in the Gsoc boardroom being connected to an external wi-fi network, the ombudsman said its internal network should not have been accessed from outside.

The watchdog said its wi-fi - which could not communicate with any of its databases or electronic systems - was password protected and should not have been linked to another network without it.